HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ASSAY FOR NANOGRAM DETERMINATION OF CHLORPROMAZINE AND ITS COMPARISON WITH A RADIOIMMUNOASSAY

[Chlorpromazine is widely used in the treatment of certain psychiatric disorders.] A specific and sensitive high-performance liquid chromatographic (HPLC) method for the quantitative determination of [human] plasma chlorpromazine concentrations is described. The procedure is capable of determining 1 ng of chlorpromazine/ml and is adequate for following plasma concentration-time profiles after 7 mg single i.v. doses. After a single organic extraction of the drug and an internal standard (mesoridazine) from plasma, the organic layer was transferred to a vial and evaporated to dryness at 55.degree. under N. The residue was dissolved in 200 .mu.l of HPLC grade acetonitrile. Aliquots (70-100 .mu.l) were chromatographed and the drug was quantitated in the range of 1-15 ng/ml of plasma using a fixed-wavelength UV detector. Plasma concentrations determined by the method were compared with those obtained by a previously reported radioimmunoassay specific for chlorpromazine and N-desmethylchlorpromazine. The 2 methods agreed favorably with a correlation coefficient of 0.993 and a slope of 0.994.